Walk dep tree visit exports fix for export {x, y as z} from 'module-identifier'

[gregmagolan]

I needed the following change for a build to work that contained exports such as:

export {x, y as z} from 'some-module';

Files referenced on lines like this were not being included in the bundle. I took a look at the Es6ModuleRewrite code and used that as an example to update FindModuleDependencies.java so that the files referenced in export lines like the one above are visited and end up included in the bundle.

Originally PR'd against the walk-dep tree branch: ChadKillingsworth#2.

@ChadKillingsworth has taken a look at it

[ChadKillingsworth]

Thanks for PRing this. Just a couple notes.

[ChadKillingsworth]

This is the only case we care about since I believe the only way an export has more than one child is if it exports from another module. There's no need to special case export *. While transpilation may not handle this case yet, we still want to add it to the module graph.

Can you simplify this case to that single if test?

[ChadKillingsworth]

Rather than cloning a node and revisiting, can you refactor out the ES6 import case to a function getModuleNameFromImportPath? Then you can just call that with the 2nd child and add the result to the graph.

[brad4d]

@ChadKillingsworth thanks for doing the review.
@gregmagolan I believe we're awaiting your responses to Chad's comments.
@blickly would probably be best to import this and do the internal review.

[gregmagolan]

@ChadKillingsworth Thanks for the comments. I'll work on your recommended changes today.

[gregmagolan]

@ChadKillingsworth Pushed the refactored changes. Ended up adding two functions to capture the common functionality for import and export statements: addEs6ModuleImportToGraph and getEs6ModuleNameFromImportNode. Not sure if the naming is ideal.

Tested it against https://github.com/gregmagolan/closure-export-example.

Also tested with an export * from 'path' statement to ensure the compile still failed with: ERROR - ES6 transpilation of 'Wildcard export' is not yet implemented.

[ChadKillingsworth]

LGTM. Assigning to @blickly for import.

[ChadKillingsworth]

@gregmagolan can you squash your commits? Importing multiple commits is known to cause problems.

[gregmagolan]

@gregmagolan can you squash your commits? Importing multiple commits is known to cause problems.

Done

[blickly]

Is it possible to add a test of this?
I think that the exiting CompilerTest.testProperEs6ModuleOrdering is the most similar existing test. See:
https://github.com/google/closure-compiler/blob/master/test/com/google/javascript/jscomp/CompilerTest.java#L1466-L1525

[gregmagolan]

Is it possible to add a test of this?

Added testProperEs6ModuleOrderingWithExport

[blickly]

Great, thanks!

Importing now...